It was rolled out to me. I saw several warnings that my ad blocker wasn't allowed, and on one day they blocked me from watching videos, except that they didn't block me from watching videos in Incognito Mode.

On all other days, I was free to watch whatever I wanted while logged in. They might complain at me about ad blocking, or not.

On all days, youtube-dl worked fine. (This matters because, contemporaneously with the anti-ad-blocking campaign, YouTube started sometimes reducing my video frame rate to 0 fps. Audio never suffered at all.)

It's not a strict regime.

It is not, but it did prompt a discussion with my buddies. What do we do when/if it becomes strict? Solutions are kinda there depending on what you are willing to put up with. FWIW, I started archiving stuff with ydl.

I have it rolled out to one of my two computers. Same IP, same google account (logged in). So it seems very random.